The present disclosure relates generally to wellsite operations. In particular, the present disclosure relates to formation evaluation involving testing, sampling, monitoring and/or analyzing downhole fluids.
Wellbores are drilled to locate and produce hydrocarbons. A downhole drilling tool with a bit at an end thereof is advanced into the ground to form a wellbore. As the drilling tool is advanced, drilling mud is pumped through the drilling tool and out the drill bit to cool the drilling tool and carry away cuttings. The fluid exits the drill bit and flows back up to the surface for recirculation through the drilling tool. The drilling mud is also used to form a mudcake to line the wellbore.
During a drilling operation, various downhole evaluations may be performed to determine characteristics of the wellbore and surrounding formations. In some cases, the drilling tool may be provided with devices to test and/or sample the surrounding formations and/or fluid contained in reservoirs therein. In some cases, the drilling tool may be removed and a downhole wireline tool may be deployed into the wellbore to test and/or sample the formations. These samples or tests may be used, for example, to determine whether valuable hydrocarbons are present.
Formation evaluation may involve drawing fluid from the formations into the downhole tool for testing and/or sampling. Various devices, such as probes or packers, may be extended from the downhole tool to establish fluid communication with the formations surrounding the wellbore and to draw fluid into the downhole tool. Downhole tools may be provided with fluid analyzers and/or sensors to measure downhole parameters, such as fluid properties. Examples of downhole devices are provided in U.S. Pat. No. 7,458,252, U.S. Pat. No. 8,024,125, U.S. Pat. No. 6,274,865, U.S. Pat. No. 6,301,959 and U.S. Pat. No. 8,322,416, the entire contents of which are hereby incorporated by reference herein.